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David B. Carlon, Patrick Warner, Clay Starr, David J Anderson, Zakir Bulmer, Hugh Cipparone, Jesse Dunn, Caroline Godfrey, Claire Goffinet, Miranda Miller, Charlotte Nash
Several shell diseases are impacting a variety of decapod crustaceans in southern New England, but have rarely been reported in the colder waters of the eastern Gulf of Maine. Here we document a possible outbreak of shell disease impacting Cancer borealis (Jonah Crab) on Kent Island, NB, Canada. On low tides of 31 August 31–3 September 2017 we found hundreds of Jonah Crabs stranded above the tide line and resting on top of the dense canopies of fucoid algae. Closer inspection of exoskeletons revealed the clinical signs of classical shell disease: dark circular patches and lesions that penetrated the cuticle. A sample of 30 stranded Jonah Crabs revealed that 28 (93%) were adult females. On the next low tide, we found the same pattern of exposed Jonah Crabs and observed numerous instances of Larus smithsonianus (Herring Gull) predation. Continuous monitoring of shallow-water temperatures over the last 3 years revealed that average daily summer temperatures have been regularly exceeding a shell-disease threshold of 12 °C on Kent Island. Between 13 September and 31 October 2015 there were 19 days with an average water temperature above 12 °C and 43 days during the same interval in 2016.
Glyptemys insculpta (Wood Turtle) populations are declining as habitat is developed and individuals are collected for the pet trade. Information about the natural history and life history of the species can help inform conservation strategies, especially for populations about which little information is currently available. Because basic ecological information is lacking for populations in the Central Appalachians, we studied the natural history of Wood Turtles in West Virginia from 2009 to 2011. Wood Turtle males were larger than females in carapace length and width, bridge height, and mass. Turtles were primarily terrestrial in spring and summer and aquatic in autumn and winter. Aquatic mating was most prevalent in autumn. Nesting attempts, which were mostly in sandy substrates, were made in spring during early morning and evening. Slugs made up the majority (67%) of the turtles' diet, although other invertebrates, vertebrate remains, berries, and green leaves were also consumed. In autumn, turtles entered the river for brumation. This study adds to our understanding of the natural history of Wood Turtles near the southern extent of their range.
Calonectris diomedea (Cory's Shearwater) are observed in small numbers in Atlantic Canada every year. However, in 2016 and 2017, unusually high numbers were reported in both Nova Scotia and Newfoundland and Labrador, Canada. We used data from eBird and from standardized ship-based surveys to document the timing and magnitude of the increase. Results show that densities have been increasing in waters off Nova Scotia since 2007 and are now of similar magnitude to those observed on George's Bank in the late 1980s, which suggests that birds are targeting cooler, more productive waters on the Scotian Shelf during migration. Continued monitoring using a variety of survey techniques will help identify important marine areas for this trans-equatorial migrant, and identify potential threats as birds move into areas not previously explo ited.
Cobscook Bay is an 11- km2 geographically complex, boreal, and macrotidal bay in eastern Maine. The physical environment, primary producers, and invertebrate assemblage of the bay are well-characterized, but no contemporary data exist on its finfish assemblage. We sampled the finfish assemblage of Cobscook Bay from 2011 to 2013 in May, June, August, and September to create a baseline dataset suitable for future comparisons. We also examined the composition, diversity, and annual changes in the assemblage. We sampled in the subtidal and intertidal zones using seines (n = 390), fyke nets (n = 72), and benthic (n = 112) and pelagic (n = 111) trawls; sampling was divided among the bay's 3 different sub-bays. We collected more than 60,000 individuals from 46 species. We employed species richness, Simpson's index of diversity, and non-metric multidimensional scaling (with the Bray—Curtis and Horn—Morisita indices) to examine spatial and temporal variation of finfish assemblages throughout the bay. Our analysis suggested that data collected in the subtidal pelagic were not a representative sample of that assemblage. Therefore, we considered 2 assemblages: the intertidal and subtidal benthic. Assemblage composition and species' relative abundances were different at diel, monthly, and annual timescales and were associated with changes in the catch rate of ubiquitous species. In the intertidal, these species included Gasterosteus aculeatus (Threespine Stickleback), Clupea harengus (Atlantic Herring), Alosa pseudoharengus (Alewife), and Menidia menidia (Atlantic Silverside). In the subtidal, the common species were Atlantic Herring and Pseudopleuronectes americanus (Winter Flounder). Statistical analyses indicated that both spatial and temporal factors were significant predictors of assemblage evenness. The sampling design, albeit complex, was sufficient to capture these differences and characterize these assemblages. Implications for future studies are that the study design must be sufficiently complex to capture the anticipated spatial and temporal variability inherent in such dynamic environments. Furthermore, given recent warming trends in the Gulf of Maine, this study's results suggest the importance of thoroughly understanding local temporal and ecosystem variability.
We report morphometric and demographic characteristics of 2 distinct populations of Glyptemys insculpta (Wood Turtle), at the northwestern periphery of the range in Canada, where they are designated as a species at risk. Our surveys of the 2 study watersheds (2012–2015) were assisted by a trained canine unit which was demonstrably more efficient than human crews in detecting Wood Turtles. We observed that both populations were large—214 and 114 uniquely marked individuals documented over time. We found no significant differences (P ≥ 0.05) in age structure, sex ratios, sexual size-dimorphism, body condition, number of observed mating attempts, or frequency and type of injuries between populations. We observed female-biased sex ratios in both populations (1:1.47 and 1:1.84, respectively) that were not attributable to sampling bias. Our data generally support the postulate of an inverse relationship between Wood Turtle body size and number of frost-free days or latitude. The general health of the 2 study populations was evidenced by the numerous large and reproductively mature individuals of both sexes, relatively high percentage of juveniles observed (average = 26%), and size-class frequency distributions that indicated sustained juvenile recruitment over several years in both watersheds. Our data suggest that high-quality forested watershed habitats, even at the northwestern extreme of the species range in Canada, can and do support large, healthy populations of Wood Turtles.
We assessed the density and productivity of Parkesia motacilla (Louisiana Waterthrush) at 4 Tsuga canadensis (Eastern Hemlock)-dominated headwater streams representing 2 distinct stream morphologies: ravines, defined by steep banks and fast-flowing water; and benches, characterized by braided streams meandering across a flat floodplain. The Louisiana Waterthrush is an established bioindicator of headwater-stream ecological integrity used to investigate overall habitat quality. We conducted the study from 2010 to 2013 in the Appalachian Highlands of northeastern Pennsylvania. Pair density and number of fledglings produced per km of study stream were exceptionally high at the 2 bench sites compared with the literature, and were significantly higher than in ravine sites, in part due to significantly higher nest survival on benches (69%) compared to ravines (33%). Double brooding was also significantly higher on benches. Differences in density, productivity, and nest survivorship between ravines and benches in our limited study suggest that benches may be of higher quality for this species. Our results have conservation and management implications regarding threatened Eastern Hemlock ecosystems, and the topic warrants further investigation.
We assessed annual growth of Coregonus clupeaformis (Lake Whitefish) from a natural, lightly exploited population in a small lake in northern Maine using observed and back-calculated length-at-age data. We sampled Lake Whitefish from Clear Lake, ME, with gill nets and extracted otoliths from 57 fish. We incorporated age-at-length data into a von Bertalanffy growth function, which we employed to model growth trajectories from individual fish. We used these estimates to evaluate length-at-age variability within this population. Ages for Lake Whitefish varied from 8 y to 30 y. Among all fish, we characterized incremental growth by an average-growth coefficient of K = 0.156 and an estimated L∞ of 484 mm. The oldest individuals demonstrated the slowest incremental growth (K = 0.106) when compared to younger cohorts (K = 0.218). We observed an inverse relationship between L∞ and K and the estimated age-at-capture (R2 = 0.178 and 0.723, respectively), which suggests relatively slow growth and a smaller maximum size for the longest living members of the population. Our estimated parameters serve as a reference to inform management of populations of Lake Whitefish.
From 1996 to 2011, researchers observed Phoca vitulina concolor (Western Atlantic Harbor Seal) on regional overwintering grounds in the Great Bay–Mullica River estuary in southern New Jersey. Over this 15-y time series, 299 observations were completed, with maximum local abundance increasing from 100 individuals in 1996 to 160 individuals in 2011. Our study did not document the presence of Atlantic Harbor Seal pups. In addition, we analyzed 142 scat samples, resulting in 1419 sagittal fish otoliths recovered and identified. Dominant recovered otoliths were as follows: 48% Phycidae (Urophycis regia [Spotted Hake]/Urophycis chuss [Red Hake]; 25% Clupeidae (Clupea harengus [Atlantic Herring], Alosa sapidissima [American Shad], Brevoortia tyrannus [Atlantic Menhaden], A. pseudoharengus [Alewife], and A. aestivalis [Blueback Herring]); 13% Ammodytidae (Ammodytes americanus/A. dubius [sandlance]); 6% Pseudopleuronectes americanus (Winter Flounder); and 4% Scophthalmus aquosus (Windowpane Flounder). Average back-calculated prey lengths across all prey groups (min–max = 5–41 cm, average = 19.75 cm) indicated that Western Atlantic Harbor Seals might utilize both estuarine and ocean environments for foraging. This temperate estuary currently represents the southern limit of routine Western Atlantic Harbor Seal occupancy in the Northeast. As such, our results are valuable in monitoring future changes in habitat use potentially resulting from climate change.
Understanding forest-regeneration pathways following salvage-logging operations and windthrow disturbances is a step towards the sustainable management of forests. To accomplish this, assessment of the relative contribution of seed dispersal and post-dispersal abiotic and biotic factors in shaping post-disturbance seedling recruitment is necessary. In a temperate deciduous forest located in western Pennsylvania, we measured the seed rain over 2 years and the resulting woody-plant recruitment in 2 tornado-disturbed stands. Our data shows that the salvage logging operation and the dispersal mode of plants (wind, animal) affected the composition of the seed rain. Communities of plant recruits, in contrast, were more strongly determined by soil-cover variables than by the net inputs of seed rain. Our results indicate that salvage logging following natural windthrow events has minimal negative impacts on forest regeneration capacity.
Non-native Oncorhynchus mykiss (Rainbow Trout) have been shown to have negative effects on native salmonid populations. However, interspecific associations between Rainbow Trout and native non-salmonid species have received little attention. Cottus spp. (sculpin) are a native benthic species group that comprise an important component of many lentic and lotic ecosystems in North America. In this study, we examined seasonal habitat associations between juvenile Rainbow Trout and C. cognatus (Slimy Sculpin) in a stream in the Lake Ontario watershed in New York. There was evidence of habitat partitioning among the age classes examined, with overyearling Rainbow Trout and subyearling Slimy Sculpin occupying disparate habitat. The habitat use by subyearling Rainbow Trout and overyearling Slimy Sculpin was similar, which may increase the potential for competition between these age groups. Overyearling Rainbow Trout exhibited the highest degree of habitat selection, whereas subyearling Slimy Sculpin exhibited the least. Our observations are the first reported on the ecological associations of Rainbow Trout and Slimy Sculpin and may provide important information in instances where sculpin are being re-introduced.
Archilochus colubris (Ruby-throated Hummingbird) invariably decorate the exterior surface of their nests with living foliose lichen. Lichen fragments may be carried considerable distances, but it is unknown whether transported thalli survive at nest sites. Here we report the multi-year persistence of a transported thallus of Myelochroa aurulenta (Powdery Axil-bristle Lichen) at a hummingbird nest site. Our observation suggests that hummingbirds may be important dispersal agents for foliose lichens.
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